Written by Anne Quinn Corr, Contributing Chef

The current pop culture fascination with sourdough is often credited to the pandemic, when we were shuttered and had time on our hands. Many of those hands determined to stay busy turned to the therapeutic process of breadmaking.

Sourdough bread is made of just flour, water, salt, and starter that contains yeast and lactic acid bacteria. Key is the starter, also known as “levain,” “mother,” or “leaven”--a living fermented mixture of flour and water that incorporates wild yeast and good bacteria from the air and the flour. 

Both wild yeasts and friendly lactobacilli are naturally occurring in the environment, which is one reason why sourdough baking was so popular during the pandemic when baker’s yeast disappeared from grocery shelves. You can make starter at home, harnessing the microbes in your own environment, and cultivating it for a week or so until it is strong enough to serve you in your sourdough quest. In a healthy sourdough starter, the ratio of lactic acid bacteria to yeast is 100:1, and the starter triples or quadruples in size in a few hours at 80°F.

The active components of the starter go to work on the carbohydrates in the flour. The yeasts convert simple carbohydrates to carbon dioxide and ethanol. There are more than 1500 known species of yeasts, but baker’s yeast, Saccharomyces cerevisiae, used in baking and beer making, is the most common. Yeasts are primarily responsible for the leavening, or rising, of the dough, but they also contribute to the flavor and aroma.

Another active agent in the starter is lactic acid bacteria (LAB), which are much smaller than yeasts and primarily produce lactic acid that creates the mild, creamy, milky sourness associated with sourdough. Lactic acid balances the sharper vinegar flavor produced by acetic acid, which is a by-product of fermentation. Lactic acid also lowers the pH (increases acidity) of the starter and activates enzymes that condition the gluten. The acidic environment serves as a natural preservative, protecting the starter and extending the shelf life of the baked bread.

Some of the proven health benefits of including sourdough in your daily diet are:

·      Digestive aid: Sourdough helps support a healthy gut microbiome because the fermentation process produces probiotics, i.e., beneficial bacteria that aid in digestion. Sourdough starters contain probiotics due to the lactic acid bacteria (Lactobacillus) and wild yeast. The sourdough fermentation process transforms carbohydrates in flour into complex compounds and resistant starches. These compounds act as prebiotics, or food for the good gut bacteria.  

·      Lower glycemic index: Sourdough lowers the glycemic index because the lactic acid bacteria break down starches and alter the carbohydrate structure so your body digests them more slowly, which prevents blood sugar spikes. The fermentation process also alters the gluten and starches in the flour, slowing digestion.

·      Nutrient absorption: Lactic acid lowers phytic acid, an antinutrient present in wheat that slows mineral absorption.

Worldwide studies abound on sourdough, though most are on bread. But the ubiquity of the sourdough phenomenon is driving new research in “novel foods.”  That same starter used for bread can be incorporated into noodles, pasta, crackers, biscuits, cookies—virtually anything flour-based.

Sourdough is the most ancient of the leavening processes, and dates to the Fertile Crescent, where Egyptian hieroglyphs depict the process of breadmaking 5,000 years ago.

It’s not hard to envision the “discovery” that a mixture of ground grain and water destined to be baked on a hot stone for flatbread was forgotten overnight and underwent a metabolic change by morning. The mixture would have been airy and alive with wild yeasts and bacteria creating carbon dioxide, bubbling away. Suppose the baker had no grain left and decided to bake it anyway, and threw it on the hot stone. The resultant bread would be fluffy and chewy, rather than flat and cracker-like. It was the dawn of the sourdough era.

Fast forward a few thousand years to find many Biblical references to bread, both in the Old and New Testaments. Jesus’ first miracle of the loaves and the fishes is digestible when one understands just how voluptuous sourdough is, and how rapidly it can reproduce. A thousand loaves from 5? No problem.

In ancient Rome, writing around 77 CE, Pliny the Elder documented Romans leavening their bread by saving some of the dough from the previous day’s bake, a method called “backslopping.” He also documented specific recipes for special sourdough breads like Picenum Bread in his encyclopedic Naturalis Historia.

Until about 200 years ago, sourdough was the primary method of breadmaking on every continent. Bread traditions were based on available grains and climate, so sourdough traditions look different in various locations. Northern Europe grows rye, which lacks gluten, so the sourdough needs a highly acidic environment for the dough to rise. In France and Italy, the doughs are primarily wheat-based for light crusty baguettes and sweet panettone. Asia relies on wheat-based sourdough as well as fermented rice batters and sponge methods for dosa and steamed buns. In Northern Africa, Egyptian leavened breads continue their tradition started at the dawn of bread history while Oceania and South America have adopted European methods due to colonization.

Moving forward in Europe, barm, ale yeast in the foam on a fermenting barrel of beer or wine, was used during the Middle Ages as a leavening agent for bread. During the late 1600s, Antonie van Leeuwenhoek refined the microscope to study single-cell organisms that he called “animacules” from his person and environment. Louis Pasteur took microbiology a step further in 1857 with his studies on yeast, which made commercial baker’s yeast feasible and threw a blanket over sourdough ascendancy.  

In North America, European settlers brought sourdough to the continent, and it spread west rapidly during the Gold Rush, establishing an entire culture dedicated to the art of sourdough baking. San Francisco was and still is the epicenter of the sourdough movement in America, with the oldest establishment, Boudin Bakery, still operating today and using a starter from 1849. (The local sourdough there features lactobacillus sanfranciscensis, first catalogued in the 1970’s.) Prospectors headed to Alaska and the Klondike region in 1880 took sourdough tucked into their belts to keep it at body temperature.

My own sourdough story started 47 years ago when I brought back a sourdough starter from Alaska and kept it going for many years. But keeping sourdough requires commitment. You need to tend it and use it regularly to keep it viable. At the time, with three kids, a husband, two dogs, a fledgling catering business, and a freelance writing sideline, something had to go.

I reprised my sourdough keeping several months ago to get up close and personal with the process, but used it only to make crackers and noodles. There are so many excellent sourdough bread options in our area, and my sisters and sister-in-law are sourdough bakers par excellence. I went another direction.

The sourdough crackers were fun to experiment with and very tasty. The noodles were extraordinary. There’s a bite to a sourdough noodle, a pleasant chewiness, and acidity that regular egg noodles don’t have. They feel substantial, nourishing; like you are doing something good for your body. Sourdough noodles are easier to digest, help to prevent insulin spikes by slowing the blood sugar absorption, reduce FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) in the grain, decrease phytic acid levels so that minerals are more bioavailable, and create resistant starches that act as prebiotics to feed healthy gut bacteria as they pass through the digestive tract. All the same benefits as sourdough bread.

Only you don't have to make sourdough egg noodles. Grandma's already on it — we've got a heritage sourdough noodle in the works. Keep an eye out, it's coming soon 👀